KR20230098612A - A device for increasing the flow capacity of a fluid channel - Google Patents

Abstract

The fairing 302 in the form of a contoured limit submerged on the fluid channel surface 304/308 of the fluid channel 300 through which the liquid flows is the velocity fields upstream and in some embodiments downstream of the discontinuity 110. fields and flow geometries, thereby preventing flow separation 207, reducing cavitation potential, and increasing flow capacity. Such discontinuities 110 include joints such as elbow joints 100, T-joints 1500 and Y-joints; valve-trims 1200; inlet areas for centrifugal pumps; and entry areas for rotary valves, steps, reductions, expansions and ledges. Fairing 302 may fit into channel 300 or be integrally fabricated with channel 300 .

Description

A device for increasing the flow capacity of a fluid channel

The present invention relates to fluid mechanics, and in particular to reduce or prevent cavitation around joints, valves and other geometric discontinuities, for example fluid channels. It relates to pairing to increase the flow capacity of a channel.

Maximizing the liquid flow capacity through fluid management devices such as valves, pipes, instruments, pumps, etc. (collectively fluid channels) has been a long-standing industry challenge to designers. Limitations on flow capacity are generally due to, among many factors, physical properties and properties such as static pressure, temperature, viscosity, surface tension, vapor pressure of the flowing fluid, the presence and flow of solids, among others. It is affected by the path geometry. Consideration of these factors leads to designs that reduce cavitation and pressure drops across components during operation at high flow rates.

Cavitation is a phenomenon where a pressure change in a liquid leads to the formation of small vapor-filled cavities at locations where the local pressure of the fluid is reduced below the vapor pressure of the liquid. Later, when subjected to higher pressures, these cavities can collapse and generate shock waves. Collapsing cavities near metal or flow boundary surfaces induce cyclic stress through repetitive implosions. This causes damage to the surface and in some cases significant physical damage. These pressure changes often occur near bends in pipes and other tortuous fluid channel paths where sudden changes in the direction of fluid flow occur. Cavitation is a significant cause of component damage in some engineering situations.

Extensive work in the design of control valves has resulted in several cavitation-reducing devices and strategies, which eventually led to guidance in the form of industry standards [1]. Currently available cavitation-reducing devices and strategies include cage trims [2, 3], hardened trim materials to withstand the effects of cavitation [4], and cavitation and undesirable pressure drops to occur. Includes generally increased overall sizes and volumes of transition regions. These devices and strategies often require specialized and expensive manufacturing techniques and/or contribute to increased cost due to increased size of the resulting equipment.

Beyond applications in pipes, valves, instruments and pumps, techniques for improving fluid flow have been used in aeronautics for decades. For example, leading edge slats, Fowler flap designs and vortex generators applied at specific locations on airplane surfaces improve air flow characteristics. The dimpled surface of a golf ball provides another example of a structural feature configured to improve gas flow around a contained object. In each of these examples, flow separation, i.e., separation of the flowing fluid from the surface, is reduced, resulting in improved performance. Nevertheless, conventional liquid-carrying channels such as pipes, fittings and valves are frequently damaged by cavitation. Therefore, a need exists for a device for increasing the flow capacity of a fluid channel.

One embodiment of the present invention provides a device for increasing the flow capacity of a fluid channel (300) in a downstream direction (310). The fluid channel has channel surfaces 304 and 308. The channel surfaces are configured for liquid flow along them. The channel surface includes a discontinuity (110). The device includes pairing (302). Fairings 302 define respective fairing surfaces 312 . The fairing surface is located entirely within the fluid channel. The fairing surface is configured for liquid flow along it. The fairing surface extends from each leading edge 400 of the fairing surface located upstream 306 of the discontinuity to each trailing edge 402 of the fairing surface located downstream of the leading edge. . The fairing surface extends at least to the discontinuity.

At the leading edge, the fairing surface abuts the channel surface. At the trailing edge, the fairing surface abuts the channel surface. The fairing surface follows a curve that transitions smoothly between the leading and trailing edges.

Optionally, in certain embodiments, the fairing surface follows a reverse curve that transitions smoothly between leading and trailing edges.

Optionally, in any embodiment, the trailing edge of the fairing surface is located no more downstream than the discontinuity.

Optionally, in any embodiment, the trailing edge of the fairing surface is downstream of the discontinuity.

Optionally, in any embodiment where the trailing edge of the fairing surface is downstream of the discontinuity, the fairing surface follows at least a 2-cycle inverse curve.

Optionally, in any embodiment, the fluidic channel defines a volume 109 configured for liquid flow therethrough, wherein at least a portion of the fairing surface between the leading and trailing edges is a virtual channel surface of the non-fairing channel. is displaced from the hypothetical channel surface into the volume of the fluid channel by a positive distance measured perpendicularly in the downstream direction.

Optionally, in any embodiment, the fluid channel defines a volume 109 configured for liquid flow therethrough, and at each location along the downstream direction, between the leading and trailing edges, the fairing surface is is displaced by a positive distance measured perpendicular to the downstream direction from the virtual channel surface of the free channel into the volume of the fluid channel.

Optionally, in any embodiment, at each corresponding position between the leading edge and the trailing edge, along the downstream direction, a cross-sectional cross-section of the fluid channel, measured perpendicular to the downstream direction and taking into account fairing ) fluid flow area is less than or equal to the imaginary cross-section fluid flow area without fairing.

Optionally, in any embodiment, the discontinuity is by a portion of a fluid channel that (a) has an elbow-shape, T-shape or Y-shape, or (b) includes an inlet area to a centrifugal pump or rotary valve. is defined

Optionally, in any embodiment, the fairing is configured for permanent or temporary installation in a fluidic channel.

Optionally, in any embodiment, the fairing is formed as an integral part of the fluidic channel.

Optionally, in any embodiment, the fairing surface is smooth.

Optionally, in any embodiment, the fairing surface is dimpled, roughened, or patterned.

Optionally, in any embodiment wherein the fairing surface is dimpled, roughened, or patterned, the fairing surface emits an acoustic signal in response to the flow of the fluid along it, representing a predetermined flow characteristic of the fluid. Defines a surface pattern configured to cause

Optionally, in certain embodiments, the fairing includes a pin 900 and the fairing is configured to pivot about the pin 900 .

Optionally, in any embodiment, the fairing defines a hollow portion 1000 and an aperture 1002 between the hollow portion 1000 and the fluid channel 300 . Hollow portion 1000 and aperture 1002 are configured to emit an oscillating acoustic signal in response to fluid flow across aperture 1002 .

Optionally, in certain embodiments, the fairing defines a bladder 1102 in fluid communication with the control port 1106. The bladder is configured to change the shape of the surface 312 of the fairing 302 in response to inflation of the bladder 1102 .

Optionally, in any embodiment in which the fairing defines a bladder, the fairing 312 defines at least one pressure sensing port 1108 fluidically coupled to each gauge port 1110. do.

Optionally, in any embodiment that includes a gauge port 1110, the gauge port 1110 is fluidly coupled to the control port 1106.

Optionally, in any embodiment, the pairing defines at least one passageway 1200 - 1202 through the fairing 302 . Each passage 1200 - 1202 fluidly connects a respective upstream portion of fairing 302 to a respective downstream portion. Each passageway 1200-1202 defines a respective upstream opening 1204-1206 and a respective downstream opening 1208-1210. Each passageway 1200 - 1202 is configured to allow at least a portion of the liquid flowing within the fluid channel 300 to bypass the entire profile of the fairing 302 .

Optionally, in some embodiments, fairing 302 includes an upstream portion 1300 and a downstream portion 1302 connected together by a pivot hinge 1304. An upstream end of upstream portion 1300 is translatably attached to channel surface 304 . The two portions 1300 and 1302 pivot in response to translation of the upstream end of the upstream portion 1300, thereby pivoting hinge 1304, the downstream end of the upstream portion 1300, and the upstream end of the downstream portion 1302. It is configured to further extend into the fluid channel 300. The fairing 302 further includes a spring 1318 configured to urge the upstream end of the upstream portion 1300 to a neutral position.

Optionally, in some embodiments, pairing 302 defines a first bladder 1402 and a second bladder 1404 . The first bladder 1402 is in fluid communication with a port 1410 downstream of the fairing 302 in the fluid channel 300 . Second bladder 1404 is in fluid communication with port 1412 upstream of fairing 302 in fluid channel 300 . The first and second bladders 1402 - 1404 are configured to automatically adjust the shape of the fairing 302 based on respective pressures at the ports 1410 - 1412 .

Optionally, in any embodiment, the channel surface includes a second discontinuity 1506. The device further includes a second pairing (1600). The second fairing 1600 defines a respective second fairing surface 1602 . The second fairing surface is located completely within the fluid channel. The second fairing surface is configured for liquid flow therethrough. The second fairing surface is formed from each leading edge 1604 of the second fairing surface located upstream 1606 of the discontinuity 1506 to each trailing edge 1608 of the second fairing surface located downstream of the leading edge. is extended to The second fairing surface extends at least to discontinuity 1506 .

At the leading edge 1604, the second fairing surface 1602 abuts the channel surface. At the trailing edge 1608, the second fairing surface 1602 abuts the channel surface. Second fairing surface 1602 follows a curve that transitions smoothly between leading edge 1604 and trailing edge 1608 .

The invention will be more fully understood by referring to the following detailed description of specific embodiments in conjunction with the drawings. In the drawings:
1 is a cross-sectional view of a prior art fluid channel including a 90 degree elbow joint and pipes running in and out of the elbow joint;
2 is a cross-sectional view of the fluid channel of FIG. 1 including streamlines representing fluid flowing through the fluid channel, according to the prior art.
3 is a cross-sectional view of a fluid channel similar to that of FIGS. 1 and 2, except for a fairing installed in the fluid channel, according to one embodiment of the present invention.
4 is an enlarged view of the fairing of FIG. 3 including a portion of a fluidic channel, according to one embodiment of the present invention.
5 is a further enlarged view of the pairing of FIGS. 3 and 4, in accordance with one embodiment of the present invention.
6 is a cross-sectional view of a fluid channel similar to that of FIGS. 3-5, except for a modification of the fairing installed in the fluid channel, in this case the fairing spanning a discontinuity, according to one embodiment of the present invention.
7 is a cross-sectional view of the fairing and fluid channel of FIGS. 3-5 showing radii of curvature of the surface of the fairing at various locations between the leading and trailing edges of the fairing surface, in accordance with one embodiment of the present invention.
FIG. 8 is a cross-sectional view of the fluid channel of FIGS. 1 and 2 showing radii of curvature of the surface of the channel without a fairing, in positions corresponding to those in FIG. 7, according to the prior art.
9 is a cross-sectional view of a portion of the fluid channel of FIGS. 3-5, minus the fairing mounted to pivot about a pin, in accordance with one embodiment of the present invention.
10 is a cross-sectional view of a portion of the fluid channel of FIGS. 3-5, excluding a hollow portion and a fairing defining an aperture leading into the hollow portion, in accordance with one embodiment of the present invention.
11 is a cross-sectional view of a portion of the fluid channel of FIGS. 3-5, excluding the fairing including an inflatable bladder for changing the shape of the fairing, and an optional pressure sensing port, in accordance with one embodiment of the present invention.
12 is a cross-sectional view of a portion of the fluid channel of FIGS. 3-5, excluding the fairing including one or more passageways connecting each upstream portion of the fairing to each downstream portion, in accordance with one embodiment of the present invention.
13 is a cross-sectional view of a portion of the fluid channel of FIGS. 3-5, excluding the two pivotally connected portions and the fairing comprising a sliding bracket, in accordance with one embodiment of the present invention.
14 is a fairing including multiple bladders in fluid communication with respective ports in a fluid channel to automatically adjust the shape of the fairing based on respective pressures at the ports, in accordance with one embodiment of the present invention. A cross-sectional view of a portion of the fluid channel of FIGS. 3-5, except for .
15 is a cross-sectional view of a fluid channel similar to that of FIG. 1 , except for the T-joint, including streamlines representing fluids flowing through the fluid channel, according to the prior art.
16 is a cross-sectional view of the fluid channel of FIG. 15 excluding fairings installed in the fluid channel, according to one embodiment of the present invention.
17, 18 and 19 are top, side perspective and side views, respectively, of an exemplary fairing, according to one embodiment of the present invention.
20 is a graph characterizing volume flow rate versus pressure drop in an exemplary application of the fairing of FIGS. 17-19, in accordance with one embodiment of the present invention.
21 is a perspective view of a portion of a conventional multi-stage cavitation mitigation globe and angle valve trim according to the prior art.

Embodiments of the present invention introduce one or more fairings into the flow field upstream and/or downstream of geometric discontinuities that can cause degradation in liquid flowing through the flow field of a fluid channel. Such discontinuities include, but are not limited to, sudden changes in direction, such as elbows, Ts, Ys, valve trims, and inlet or outlet regions of centrifugal pumps and rotary valves. The flowing liquid may, but need not have, have a free surface, at least when the fairing is performing its function, the fairing may be intended to be completely submerged in the liquid. The presence of one or more fairings improves flow performance, such as promoting higher flow rates for a given pressure drop, reducing flow separation and/or reducing cavitation.

Through the use of hydrodynamically designed channel restrictions, pairings improve liquid flow characteristics where flow separation, cavitation or other discontinuities limit performance.

definitions

As used in this description and the appended claims, the following terms shall have the meanings indicated unless the context requires otherwise.

A “fluid channel” is a passage through which a liquid can flow. The term "liquid" includes a slurry as well as a liquid with suspended or entrained particles or gases. Examples of fluid channels include pipes, pumps, valves, and fittings such as elbows, T-joints and Y-joints. The fluid channel surrounds and retains the liquid flow perpendicular to the flow direction of the fluid. Fluid channels define a cross-sectional area and volume through which liquid flows. Generally, the liquid is in contact with the interior surface of the fluid channel, but the liquid may define a free surface that does not contact the interior surface of the fluid channel. For example, in a pipe that is only partially filled with liquid, the liquid defines a free surface that is in contact with the interior, typically lower surface, of the pipe, but the liquid also does not contact the interior surface of the pipe.

A "discontinuity" (also referred to herein as a "geometric discontinuity") is a geometric or other feature of a fluid channel that causes a change in the pressure of a fluid flowing through the fluid channel, other than a change in pressure due to frictional losses occurring at the walls of the fluid channel. am. In a discontinuity, the streamlines of the flowing fluid do not touch the channel walls in the general direction of the flowing fluid. In many cases, the discontinuity is characterized by an abrupt change in the flow direction of the fluid moving through the channel, relative to the entire length and/or direction of the fluid channel. Examples of discontinuities are elbows, T-joints, Y-joints, steps, reductions, expansions, ledges, valve trims, inlets to centrifugal pumps, and inlet and outlet areas to valves.

The “limit” of a fluid channel is the area of the channel that decreases in volume per unit length of the channel.

A “vena contracta” is the point in a fluid stream where the diameter of the stream is minimum and the fluid velocity is maximum, such as in the stream exiting the nozzle. Vena contracta can arise from flow restrictions that arise from geometric discontinuities within the fluid channels. Flow streamlines cannot abruptly change direction in such a discontinuity, which causes them to converge, resulting in flow narrowing, flow separation and ultimately cavitation.

A “pairing” is a device that creates a contoured restriction of a fluid channel. The fairing can be a component separate from the channel that fits on the inner surface of the channel to form the contoured limits of the channel, or the fairing can be manufactured as an integral geometric part of the channel, i.e. a unit with the fluid channel. there is.

An "inverse curve" (S-shaped curve) is a curve in the opposite direction following a curve to the left or right.

"Resilient" means capable of absorbing energy when elastically deformed, and releasing at least some of that energy as it recoils or springs back to shape upon unloading.

A surface that is “concave along the direction of liquid flow” is one that expands outward along the path of liquid flow, just as the diameter of a pipe or tube locally expands due to internal pressure.

A surface that is “convex along the direction of liquid flow” is one that contracts inward along the direction of liquid flow, such as when the diameter of a pipe or tube is locally compressed due to external pressure. Thus, as illustrated in FIG. 1 , in an elbow, the concave inner wall has a larger radius, such as at 101 , than the radius of the convex inner wall, such as at 110 . Pairing enlarges or otherwise modifies a convex surface.

An “integral” geometry or “integral” portion of a fluid channel describes a structure that is configured as a piece with a fluid channel. This integral geometry is distinct from structures that are formed separately from the fluid channels and later fit into the fluid channels.

pairing

As noted, embodiments of the present invention introduce one or more fairings into the flow field upstream and/or downstream of geometric discontinuities that can cause performance degradation in liquid flowing through the flow field of a fluid channel. The upstream fairing is (a) a smooth transition from the inner surface of the fluid channel upstream of the discontinuity, and (b) a smooth transition to the inner surface at or downstream of the discontinuity in the direction of the flow streamlines. characterized by

The fairing may have a surface between the transition regions that is smooth, dimpled, rough, or patterned with static geometrical features. These features may be needed for assembly and installation, to regulate (increase or decrease) turbulence levels, to aid in heat transfer, to capture entrained solids or gases, or to provide feedback for flow control. It can be designed to function as a Helmholtz resonator that emits an acoustic signal that can be measured.

The interior volume of the fairing need not be solid, but may include a cavity or series of cavities. In some embodiments, the cavities within the fairing are connected to each other and/or to flow regions upstream and/or downstream of the fairing, and/or to fluid or gas reservoirs outside the fairing and the flow field, and/or to instruments. can be interconnected.

The cavities within the fairing are for interconnection of the cavities with fluids for temperature control and/or fluid pressure, vapor pressure, viscosity, specific gravity, surface tension, temperature and/or flow rate. Space may be provided for housing instruments that monitor flow-related parameters. The cavities in the fairing can also connect to adjustable flaps that can be opened to direct moving liquid through the cavities, thereby enabling improved performance across multiple flow regimes.

The geometrical characteristics of the surfaces of the fairing may be selected according to parameters related to liquid flow such as velocity, vapor pressure, viscosity, specific gravity and surface tension. When spline curves are used to describe the curvature of a fairing surface, splines can be defined by continuous polynomials of second order or higher. However, the curvature of the fairing surface is not limited to description in terms of standard polynomials, and is not limited to ellipses, involutes, catenaries, evolutes, or any suitable mathematical or geometrical expression(s). or as part of them. A variety of functions, including polynomials, can be used to curve-fit the fairing to the expected flow profile.

The polynomial values of the transition region of the fairing can be tailored to a desired flow rate, and can vary in size and location based on the velocity, viscosity, vapor pressure, and/or other characteristics of the fluid.

Each pairing can have a single component or feature, or a pairing can be a composite of multiple components and/or features. A pairing or pairings may span the discontinuity and downstream regions.

Vanes and Differences from Conventional Vehicle Fairings

Fairings according to the invention are distinguished from vanes in at least the following respects. The vanes are designed to reduce the radius of curvature of the flowing fluid, keeping the flowing fluid closer to an existing or desired geometry (sometimes a boundary) than the fluid would flow without the vanes. In contrast, fairings according to the present invention are configured to increase the radius of curvature of the flowing fluid and/or to change the effective volume of the fluid channel in a discontinuity. Pairing can be considered to change the radius of curvature of the inner surface of the flow channel to more closely match the natural radius of curvature of the flowing fluid. Thus, the pairing is opposite to the vane. Whereas vanes are designed to alter the natural fluid flow path so that the fluid flow path follows a geometric surface, fairings alter the geometric surface to more closely follow the natural fluid flow path.

The vanes do not touch the existing flow boundary, but rather are suspended within the flow when viewed in a plane normal to the flow. Thus, the vanes are close to the flow boundary, i.e. close to the flow boundary but spaced apart from the flow boundary. Generally, as described herein, fairings contact existing flow boundaries.

The vanes do not redistribute the curvature of the existing flow boundary or redistribute the existing flow velocity profile. Pairing manipulates these properties.

The fairings described herein are distinct from conventional aircraft fairings, bicycle or motorcycle fairings, payload fairings and cable fairings. An aircraft fairing is a structure that covers gaps or spaces between parts of an aircraft to reduce form drag and interference drag and improve appearance. A bicycle fairing is a full or partial covering for a bicycle to reduce aerodynamic drag or protect the occupant from wind and rain. A motorcycle fairing is a shell placed over the frame of a motorcycle, especially a racing or sport motorcycle, with the primary purpose of reducing aerodynamic drag. Secondary functions are to protect occupants from airborne hazards and wind-induced hypothermia, and to protect engine components in case of an accident. Motorcycle fairings almost always include an integrated windshield. A payload fairing is a nose cone used to protect a spacecraft (projectile payload) from dynamic pressure and aerodynamic heating during launch through the atmosphere. A cable fairing is a structure attached to a towed cable designed to simplify flow around the cable, primarily in marine environments.

illustrative problem

1 is a cross-sectional view of a conventional 90 degree elbow joint 100, with pipes 102 and 104 running in and out of the elbow joint 100. The elbow joint 100 and pipes 102-104 collectively define a fluid channel 105. The general directions of fluid flow within fluid channel 105 are indicated by axes 106 and 108 . The fluid channel 105 defines a volume 109 through which liquid can flow. As can be seen in FIG. 1, the general direction of fluid flow changes abruptly at the elbow 100, which as discussed can cause cavitation. Elbow 100 introduces a discontinuity 110 exemplified here as a sharp corner. However, it should be noted that corner sharpness is relative. Even rounded corners can cause cavitation depending on the nature of the fluid flow with respect to the geometry and/or dimensions of the corner. Thus, as used herein, the term "discontinuous" means that the direction of fluid flowing through a fluid channel suddenly changes and, under conceivable operating conditions, that change in direction causes cavitation or affects the flow performance. It includes any place within the fluid channel that can be adversely affected.

FIG. 2 is a cross-sectional view of the elbow joint 100 of FIG. 1 , except that the streamlines 200 represent fluid flowing through the elbow joint 100 . Arrows 202 and 204 indicate directions of fluid flow. Direction 202 changes abruptly from discontinuity 110 to direction 204 . In the example shown in FIG. 2 , as a result of the abrupt change in direction, the flow streamline 200 is unable to follow the sharp edge of the discontinuity 110, resulting in vena contracta 206 and a break in the fluid channel 105. This results in a pressure drop in the streamlines 200 and flow separation 207 from the interior surface 208 . In high velocity flows, the pressure drop and wall separation 207 result in cavitation and ultimately structural damage of the fluid channel 105 .

Exemplary Embodiments

3 is a cross-sectional view of a fluid channel 300 similar to the fluid channel 105 of FIGS. 1 and 2, except for a fairing 302 installed in the fluid channel 300, according to one embodiment of the present invention. Arrows 306 and 310 indicate upstream and downstream directions, respectively. As can be seen in FIG. 3 , fairing 302 is part of fluid channel 300 upstream 306 of discontinuity 110 , for example discontinuity 110 from inner wall surface 304 of pipe 102 . ) provides a smooth transition to the portion of the fluid channel 300 downstream 310, for example to the inner wall surface 308 of the pipe 104. Accordingly, pairing 302 defines transition region 311 .

In contrast to the prior art, the fairings 302 allow fluid to flow smoothly along the surface 312 of the fairing 302 continuously around the transition regions and discontinuities 110, thereby allowing, compared to the prior art, the fluid 300 ) increases the fluid velocity at which flow separation from the surface 304 and/or 308 of the channel will occur, and decreases cavitation for a given fluid velocity. The improved flow behavior is evident from streamlines 314 . For example, at 316 it can be seen that a locally higher velocity is maintained than in the prior art, while wall contact is maintained.

3 thus illustrates a device for increasing the flow capacity of a fluid channel 300 in a downstream direction 310 . Fluid channel 300 may be two pipes 102 and 104 connected by an elbow 100, for example as discussed with reference to FIGS. 1 and 2 . The fluid channel 300 has channel surfaces 304/308 configured to allow fluid to flow along the channel surfaces 304/308. Channel surfaces 304/308 may be part of elbow 100 as well as inner wall surfaces of pipes 102 and 104. Channel surfaces 304/308 include discontinuities 110, such as sharp bends.

The device includes a first pairing (302). In normal use, the first fairing 302 should be completely submerged in the fluid flowing within the fluid channel 300 . A first fairing 302 defines a respective fairing surface 312 . Fairing surface 312 is positioned completely within fluid channel 300 . Fairing surface 312 is configured for fluid flow along fairing surface 312 .

FIG. 4 is an enlarged view of the fairing 302 of FIG. 3 , including a portion of the fluid channel 300 . 5 is a further enlarged view of only the fairing 302 . Fairing surface 312 is formed from each leading edge 400 of fairing surface 312 located upstream 306 of discontinuity 110 to fairing surface 312 located downstream 310 of leading edge 400. It extends at least to the discontinuity 110 with each trailing edge 402 of . Double arrow 404 ( FIG. 4 ) indicates the size of fairing surface 312 .

The fairing 302 varies in thickness 406 over its length 408, where “thickness” is the dimension between the fairing surface 312 and the imaginary inner wall surface 304 of the fluid channel 300 without the fairing 302. means Dimension 501 is an exemplary thickness of fairing 302 at a point along fairing surface 312 . Fairing 302 is tapered proximate leading edge 400 (ie, progressively thinner closer thereto), ideally as thin as is practical given material, manufacturing and other constraints. In the embodiment shown in FIGS. 3-5 , the fairing surface 312 proximate the leading edge 400 is convexly curved with a radius 408 ( FIG. 4 ).

In other embodiments, for example as shown in the inset of FIG. 4 , the fairing surface 312 proximate the leading edge 400 may be in the form of an inclined but straight ramp 410; It forms a relatively small angle 412 with the channel surface 304 . Angle 412 may be selected based on expected operating conditions and manufacturing practicalities. These factors can be traded off with each other. For example, angle 412 can be chosen to be thick enough to manufacture economically, yet small enough to divert flowing fluid without significantly negatively impacting performance. Typically, angle 412 is less than about 75 degrees. In some embodiments, angle 412 is less than about 60 degrees, or less than about 40 degrees, or less than about 30 degrees, or less than about 25 degrees, or less than about 7 degrees.

In either case at leading edge 400 , ie curved, stepped, or straight, fairing surface 312 is referred to herein as “tangent” to channel surface 304 . Tangent (tangent line) includes conventional mathematical and geometric meanings. However, as used herein, abutting also contemplates actual aspects of manufacture of the fairings 302 . The transition from the inner wall (channel surface) 304 to the fairing surface 312 should be smooth and continuous to the extent practical. For example, since metal, plastic and other practical materials cannot be infinitely thin, if the fairing 302 is manufactured as a discrete unit to be attached to the inner wall (channel surface) 304, the leading edge 400 will: For example, as shown in the enlarged view of FIG. 4 , a small but finite step 414 may be included. Similarly, a straight leading edge 400 that meets channel surface 304 at angle 412 is considered tangent to channel surface 304 . All embodiments described herein are within the tangential meaning. At the trailing edge 402 , the fairing surface 312 abuts the channel surface 308 using the same definition of tangent as for the leading edge 400 .

In some embodiments, for example, as shown in FIGS. 3-5 , fairing surface 312 follows an inverse curve that transitions smoothly between leading edge 400 and trailing edge 402 . For example, as best shown in FIG. 5 , in a first portion 500 of the fairing surface 312 proximate the leading edge 400, the fairing surface 312 is (as viewed in the downstream direction 310) ) follows the curve to the left 502 , and in the second portion 504 downstream of the first portion 500 , the fairing surface 312 follows the curve to the right 506 . The two segments 500 and 504 may be connected to each other by a straight segment 508 as shown in FIG. 5 . In this case, the curve is reversed along or along the straight portion 508 . Optionally, the two parts 500 and 504 can be connected to each other by curved parts (not shown), or the two parts 500 and 504 can be directly connected to each other (not shown), thus the rigor of the term. can be found in a mathematical sense.

In the embodiments shown in FIGS. 3-5 , the portion 500 of the fairing surface 312 proximate the leading edge 400 (labeled in FIG. 5 ) is linearly concave in the downstream direction 310 . This portion 500 transitions smoothly from the channel surface 304 (FIG. 4) to the trailing edge 402 of the upstream 306 of the discontinuity 110. The portion 504 ( FIG. 5 ) of the fairing surface 312 proximate the trailing edge 402 is linearly convex in the downstream direction 310 . This portion (504) in turn transitions to the channel surface (308) proximal to the discontinuity (110). As can be seen from FIG. 5 , the portion 500 of the fairing surface 312 proximate the leading edge 400 is configured to increase the radius of curvature of the flowing fluid, diverting the flowing fluid away from the channel surface 304. direct away This results in increased fluid velocity at which flow separation from the fairing surface 312 occurs, and reduced cavitation for a given fluid velocity.

Figure 6 is a cross-sectional view of a fluid channel 300 similar to the fluid channel 300 of Figs. am. The trailing edge 402 of the fairing surface 312 described with respect to FIGS. 3-5 is located no further downstream 310 than the discontinuity 110 . However, in the variation of fairing 302 shown in FIG. 6 , trailing edge 402 of fairing surface 312 is located downstream 310 of discontinuity 110 . That is, variant pairing 302 spans discontinuity 110 . Among many properties, the fairing of FIG. 6 facilitates flow in either direction (310 or 306).

The fairing surface 312 of the deformed fairing 302 shown in FIG. 6 follows an at least 2 cycle inverse curve, meaning that the curve reverses direction at least 2 times. Fairing surface 312 of FIG. 6 reverses the curve direction (to the left) at or near point 600, and fairing surface 312 curves back (this time to the left) at or near another point 602. to the right) inverted.

As mentioned, and as can be seen in FIG. 7 , the fluid channel 300 defines a volume 109 configured for liquid flow therethrough. each along the downstream direction 310 of at least a portion of the fairing surface 312 between the leading edge 400 and the trailing edge 402 illustrated by the positions of arrows 700, 702, 704 and 706; In position, the fairing surface 312 is a positive distance represented by the lengths of the arrows measured perpendicular to the downstream direction, i.e., the thickness of the fairing 302, the virtual channel without the fairing 302. It is displaced from the channel surface 708 into the volume 109 of the fluid channel 300. Thus, the fairing surface 312 follows a curve that transitions smoothly between the leading edge 400 and the trailing edge 402, so that the At least some, e.g., each of the locations 700-706, is a fluid channel 300 from the virtual channel surface 708 of the channel 300 without the fairing 302 by a positive distance, measured perpendicular to the downstream direction 310. ) is displaced into the volume 109 of As a result, fluid cannot flow closer to the virtual channel surface 708 than to the fairing surface 312 .

FIG. 8 is a cross-sectional view of a fluid channel 105 similar to the fluid channel 300 of FIG. 7 except that the fairing 302 is missing. As noted, the fluid channel 105 defines an inner wall surface 808 . The inner wall surface 808 corresponds to the virtual channel surface 708 discussed with respect to FIG. 7 . The positions of arrows 800 - 806 in FIG. 8 correspond to the positions of arrows 700 - 706 in FIG. 7 . Of course, the fluid channel 105 of FIG. 7 does not have fairings. As a result, fluid can flow along the inner wall surface 808 . That is, fluid can flow closer to, in fact directly along, the virtual channel surface 808 of FIG. 8 than fluid can flow along the virtual channel surface 708 of FIG. 7 .

As can be seen in FIG. 3 , at a number of locations along the fairing surface 312 , the fairing 302 forces fluid to flow a distance from the inner wall surface 304 , for example distance 318 . Returning to FIG. 7 , in some embodiments, between a point downstream of leading edge 400, e.g. point 716 (FIG. 7), and a point upstream of the discontinuity, e.g. point 718, At each corresponding position along the downstream direction 310, the fairing 302 has a thickness 501 measured perpendicular to the downstream direction 310 that is greater than zero, which allows the fluid to pass through the fairing 302. forces it to flow farther away from the virtual channel surface 708 than it can flow from the inner wall surface 808 without it.

In some embodiments, for example the embodiment shown in FIG. 6 , a point downstream of discontinuity 110, for example point 604, and another point upstream of trailing edge 402, for example point At each corresponding location along the downstream direction 310 between 606 , the fairing surface 312 has a thickness 608 measured perpendicular to the downstream direction 310 greater than zero, which is This forces the fluid to flow further away from the virtual channel surface 304 than it can flow from the inner wall surface 304 without the fairing 302. Note that the downstream direction 310 changes (in the example of FIG. 6 , from horizontal to vertical) near the discontinuity 110 .

Similarly, at each corresponding location along the downstream direction 310, between the leading edge 400 and the trailing edge 402, the fluid channel 300 (FIG. 3) is perpendicular to the downstream direction 310. The cross-sectional fluid flow area measured with and taking into account the fairing 302 is less than or equal to the hypothetical cross-sectional fluid flow area without the fairing 302 (FIG. 1 or FIG. 2).

Discontinuity 110 may be defined by a portion of fluid channel 300 having an elbow shape, T-shape or Y-shape. Discontinuity 110 may be defined by a portion of fluid channel 300 that includes an inlet region to a centrifugal pump or rotary valve.

Fairing 302 may be configured for permanent or temporary installation within fluid channel 300 . Alternatively, fairing 302 may be formed as an integral part of fluid channel 300 .

Fairing surface 312 can be smooth, dimpled, rough, or patterned. Fairing surface 312 may define a surface pattern configured to cause emission of acoustic signals in response to the flow of fluid along fairing surface 312 . Acoustic signals are not necessarily audible to humans. The acoustic signal may be a sound wave, infrasonic or ultrasonic. The acoustic signal may represent a predetermined flow characteristic of the fluid, such as speed, velocity, pressure or viscosity. For example, the frequency of the acoustic signal can be proportional to the speed of the fluid and/or the amplitude of the acoustic signal can be proportional to the amount of entrained solids in the fluid.

Figure 9 is a portion of a fluid channel 300 similar to the fluid channel 300 of Figs. is a cross-section of In this embodiment, fairing 302 is attached to pin 900 and fairing 302 is configured to pivot about pin 900 . In a first version of this embodiment, the fairing 302 is configured to only pivot clockwise 902 from a neutral position. In a second version of this embodiment, the fairing 302 is configured to pivot only in a counterclockwise direction 904 from a neutral position. In a third version of this embodiment, the fairing 302 is configured to pivot both clockwise 902 and counterclockwise 904 from a neutral position. Optionally, any version of this embodiment includes a spring attached to fairing 302 and configured to urge fairing 302 toward a neutral position. In some cases, the spring is a torsional spring 906 wound around pin 900 .

In use, the fairing 302 automatically pivots about the pin 900 in response to the flow rate of liquid flowing within the fluid channel 300 . As discussed with respect to FIG. 3 , a high flow rate causes the fairing 302 to automatically pivot in a counter-clockwise direction 904 , thereby automatically matching the flow streamlines of the liquid and channel surface 308 . to prevent flow separation from

FIG. 10 is an illustration of a fluid channel 300 similar to the fluid channel 300 of FIGS. 3-5, except for another modification to the fairing 302 installed in the fluid channel 300, according to one embodiment of the present invention. This is a cross-section of some In this embodiment, a fairing 302 defines a hollow portion 1000 and a neck, and an aperture 1002 between the hollow portion 1000 and the fluid channel 300 . Hollow portion 1000 and aperture 1002 collectively form Helmholtz resonator 1004 . In response to fluid flowing across the mouth of aperture 1002, Helmholtz resonator 1004 emits a vibroacoustic signal, which can be detected by optional acoustic sensor 1006. and may be processed by indicator circuitry, control circuitry, alarm circuitry, collectively indicated at 1008, or other suitable circuitry. Acoustic sensor 1006 should be able to detect small pressure differences or vibrations transmitted through the perimeter walls of fairing 302 . Acoustic signals are not necessarily audible to humans. Acoustic signals may be sound waves, infrasound or ultrasound. The dimensions and shape of the hollow portion 1000 and/or the aperture 1002 can be configured such that the Helmholtz resonator ( 1004) can be selected to tune. In other cases, the dimensions and shape of the hollow portion 1000 and/or aperture 1002 may be selected to resonate with the acoustic signal from the cavitation, thereby amplifying the cavitation signal so that the signal is transmitted to the acoustic sensor 1006. can be detected by

11 is a fluid channel 300 similar to the fluid channel 300 of FIGS. 3-5, except for another modification to the fairing 302 installed in the fluid channel 300, according to one embodiment of the present invention. is a cross-sectional view of a part of In this embodiment, at least a portion 1100 of the fairing 302 is flexible, and in some cases resilient. Flexible portion 1100 forms part of bladder 1102 . Bladder 1102 defines a hollow portion 1104 in fluid communication with control port 1106 .

The bladder 1102 may be inflated or deflated by injecting or withdrawing fluid into or out of the hollow portion 1104 through the control port 1106 . Inflating or deflating the bladder 1102 changes the shape of at least the flexible portion 1100 of the fairing 302 and thereby changes the shape of the surface 312 of the fairing 302 . Control port 1106 may be fluidly coupled to a drive mechanism such as a piston (not shown) to change the shape of fairing 302 under user or program control.

Optionally or alternatively, fairing 312 defines one or more pressure sensing ports, illustrated as pressure sensing ports 1108 , that are fluidly coupled to each gauge port, illustrated as gauge ports 1110 . Pressure sensing ports 1108 may be distributed longitudinally along fairing 302 to measure respective pressures at various locations along fairing 302 . Each gauge port 1110 is a fluid pressure sensor or user-readable gauge (not shown) to monitor the pressure(s) along surface 312 of fairing 202, for example. can be combined Optionally or alternatively, one or more of the gauge ports 1110 may, for example, directly or via a normalizing valve 1112, an amplifier 1114 or a piston 1116 (each of which is shown schematically). fluidly coupled to the control port 1106 via a fluid coupling to the bladder 1102 in response to pressure(s) along the surface 312 of the fairing 302 or pressure differentials along the surface 312 of the fairing 302. It can automatically inflate or deflate.

12 is a fluid channel 300 similar to the fluid channel 300 of FIGS. 3-5, except for another modification to the fairing 302 installed in the fluid channel 300, according to one embodiment of the present invention. is a cross-sectional view of a part of In this embodiment, pairing 302 defines one or more passages through pairing 302 , represented by passages 1200 and 1202 . Passages 1200 - 1202 connect each upstream portion to each downstream portion of fairing 302 . Each passage 1200-1202 has a respective upstream opening represented by upstream openings 1204 and 1206, and each passage 1200-1202 has a respective upstream opening represented by downstream openings 1208 and 1210, respectively. has an opening downstream of

Passages 1200 - 1202 allow at least a portion of the liquid flowing within fluid channel 300 to bypass the entire profile of fairing 302 . At relatively low flow rates, a significant portion or all of the liquid flowing within the fluid channel 300 may flow through the passage 1200 closest to the inner wall surface 304 of the pipe 102 . As the flow rate increases, additional portions of the liquid flowing within the fluid channel 300 flow through additional passages 1200 - 1202 progressively further away from the inner wall surface 304 of the pipe 102 . For example, at higher flow rates, a portion of the liquid flowing within the fluid channel 300 may flow through the passageway 1200 and an additional portion of the liquid flowing within the fluid channel 300 may flow through the pipe 102 ) flows through the passage 1202 next closest to the inner wall surface 304. Thus, the fairing 302 automatically adapts to various flow rates without moving parts.

FIG. 13 is an illustration of a fluid channel 300 similar to the fluid channel 300 of FIGS. 3-5, except for another modification to the fairing 302 installed in the fluid channel 300, according to one embodiment of the present invention. This is a cross-section of some In this embodiment, the fairing 302 includes an upstream portion 1300 and a downstream portion 1302 connected together end-to-end by a pivot hinge 1304 . The downstream end of the downstream portion 1302 is attached to the inner wall surface 304 of the pipe 102 via a bracket 1308 secured by a second pivot hinge 1306. The upstream end of the upstream portion 1300 is attached to the inner wall surface 304 of the pipe 102 via a sliding bracket 1312 by a pivot 1310 . Sliding bracket 1312 is longitudinally translatable parallel to the flow direction as indicated by double arrow 1314 .

As the sliding bracket 1312 translates toward the fixed bracket 1308, the two portions 1300, 1302 of the fairing 302 pivot as indicated by the arrows. As a result, the downstream end of portion 1300 and the upstream end of portion 1302, as well as pivot hinge 1304, extend further into the flow stream of fluid channel 300, as shown by dashed lines 1316. and thereby reducing the radius of the flow stream. Translating the sliding bracket 1312 away from the stationary bracket 1308 moves the pivot hinge 1304, the downstream end of section 1300 and the upstream end of section 1302 into fluid channel 300, as shown in solid lines. ) is at least partially withdrawn from the flow stream. A spring 1318 urges the sliding bracket 1312 to a neutral or initial position.

Liquid flowing within the fluid channel 300 pushes the sliding bracket 1312 and one portion 1300 of the fairing 302 toward the stationary bracket 1308, compressing the spring 1318 and fairing 302. ) curve more aggressive. When the flow rate of the liquid decreases, the spring returns the sliding bracket 1312 and portion 1300 of the fairing 302 toward their neutral or initial positions. Thus, the fairing of FIG. 13 can be used as a flow speed regulator.

Mounting the spring 1318 on a cam (not shown) provides a nonlinear spring constant to the spring. Due to the hysteretic spring constant, fairing 302 can be used as a safety device or to limit flow through fluid channel 300 . Applications of such an embodiment include presetting the hysteretic spring constant to a value that allows for a flow rate up to a predetermined value, but the fluid channel and fairing 302 can, at least in theory, sustain a higher flow rate. The predetermined flow rate may be selected to protect other equipment or plumbing, or the predetermined flow rate may be set to a higher flow rate, and then the hysteresis spring constant may be adjusted to allow for the increased flow rate.

14 is a fluid channel 300 similar to the fluid channel 300 of FIGS. 3-5, except for another modification to the fairing 302 installed in the fluid channel 300, according to one embodiment of the present invention. is a cross-sectional view of a part of In this embodiment, at least a portion 1400 of the fairing 302 is flexible, and in some cases resilient. Flexible portion 1400 forms part of a number of bladders represented by bladders 1402 and 1404 . Each bladder 1402 - 1404 defines a respective hollow portion represented by hollow portions 1406 and 1408 . Hollow portions 1406-1408 are respectively represented by channels 1414 and 1416, to automatically adjust the shape of fairing 302 based on the respective pressure at ports 1410-1412. In fluid communication with respective ports represented by ports 1410 and 1412, downstream and upstream of fairing 302 in fluidic channel 300, via a channel of

Optionally, hollow portions 1406 and 1408 normalize the pressures in hollow portions 1406-1408, for example, if the pressure in one of hollow portions 1408 exceeds a predetermined value ( In order to normalize, for example, they are communicatively coupled to each other via a one-way valve (1418).

Pairings at Confluence of Fluid Flows

The fairing 302 of FIGS. 3-7 and 9-14 is described with respect to elbows. However, the principles of fairing 302 also apply to other types of pipe, such as T-joints, Y-joints, and other joints having multiple input ports where multiple fluid flows join together to create a single outlet. 15 is a cross-sectional view of a T-joint 1500 having two input ports 1502 and 1504. Similar to FIG. 2 , FIG. 15 includes streamlines 200 representing fluid flowing through the T-joint 1500 . The line patterns of streamlines 200 represent exemplary flow rates as indicated in the key of FIG. 15 . The flow rates shown in FIGS. 15 and 16 are intended to be representative in nature, and are explained based on analytical modeling of the flow behavior in hypothetical examples. Flow rates in other examples may be higher or lower, or may extend over different ranges than those shown in FIGS. 15 and 16 .

Arrows 202 and 204 indicate directions of fluid flows. As a result of the two abrupt changes in direction, the flow streamlines 200 cannot follow the sharp edges of the discontinuities 110 and 1506, resulting in vena contracta 206 and the inner surface 208 of the fluid channel. resulting in flow separation 207 and pressure drop in streamlines 200 from

The problems shown in FIG. 15 can occur in many situations including rotary and 3-way valves, spill ways and exhaust or relief headers. The sharp corners at the inlet and outlet regions of headers, valves, etc., and slots in rotary valves are discontinuities, and as described with respect to Figs. Causes tracta, resulting in pressure drops and flow separations from the interior surfaces. At high liquid velocity flows, pressure drops and wall separations can lead to cavitation and ultimately structural damage.

FIG. 16 shows a fluid channel similar to that of FIG. 15 except that two fairings 302 and 1600 are installed in the fluid channel 300, one fairing 302 and 1600 per input port 1502 and 1504. It is a cross section of 300. As discussed with reference to FIGS. 3-5 , fairings 302 and 1600 separate discontinuities 110 and 1506 from respective portions of fluid channel 300 upstream of discontinuities 110 and 1506 . It provides smooth transitions to the respective parts of the fluid channel 300 downstream. Accordingly, pairings 302 and 1600 define respective transition regions.

The second fairing surface 1602 is located downstream of the leading edge 1604 from the leading edge 1604 of the second fairing surface 1602 located upstream 1606 of the discontinuity 1506. ) extends at least to the discontinuity 1506 with the trailing edge 1608 of .

The fairings 302 and 1600 allow fluid to flow smoothly along the surfaces 312 and 1602 of the fairings 302 and 1600 continuously around the transition regions and discontinuities 110 and 1506, whereby the conventional Relative to the technique, flow separation from the surface of the fluid channel 300 increases the fluid velocity at which it will occur, and reduces cavitation for a given fluid velocity. The improved flow behavior is evident from streamlines 1610.

fairing shape

17, 18 and 19 are top, side perspective and side views, respectively, of an exemplary fairing 1700 according to one embodiment of the present invention. As can be seen in FIG. 17 , the longitudinal axis 1702 of the fairing 1700 is curved, although in other embodiments the longitudinal axis is straight. Concave areas 1704 and 1706 on portions of surface 1708 of fairing 1700 are also visible in FIG. 17 .

Analytical characterization of flow rate versus pressure drop at the junction of a fluid flow application in which hydrocarbons are pumped at high volumetric flow rates using the pairings of FIGS. pressure drop) can be re-equated with nearly 25% more volume flow. A typical characterization of this performance is shown in FIG. 20 .

Fairings in control valve cage trim assemblies

With the proliferation of 3D printing technology, as described herein, fairings can be manufactured in control valve cage trim assemblies and other components with corresponding improvements in fluid performance. Current cage trim designs appear to be limited to flow path profiles manufactured using traditional methods, with drilled holes, wire-cut square profile channels, and the outside of the cylinder of the trim. It includes feature sets that include features that can be milled from However, fairings according to the present disclosure may be incorporated into valve trims having integral designs, for example via additive manufacturing methods.

Conventional cavitation mitigation designs can be improved with the addition of the pairings described herein. For example, a portion of a conventional multi-stage cavitation relief glove and angle valve trim 1200 is shown in FIG. 21 (view attributed to FlowServe Corporation). Fairings (not shown) may be manufactured or installed at sharp turns in valve trim 2100 .

references

[1] SA-RP75.23-1995 - Recommended Practice - Considerations for Evaluating Control Valve Cavitation, Instrument Society of America, 1995, Research Triangle Park, North Carolina.

[2] Monsen, J., "Liquid Flow in Control Valves," Valin® blog, 1/30/2017, https://www.valin.com/resources/blog/liquid-flow-control-valves-choked- flow-cavitation-and-flashing.

[3] Roth, K.W., Stares, J. A., "Avoid Control Valve Application Problems with Physics-based Models," Hydrocarbon Processing, August 2001.

[4] Stares, J., "Control Valve Cavitation, Damage Control," Dresser-Masoneilan publication, February 2007.

Although the present invention has been described through the exemplary embodiments described above, modifications and variations to the illustrated embodiments may be made without departing from the concepts of the invention disclosed herein. Although specific parameter values, such as, for example, angles, may be described with respect to the disclosed embodiments, within the scope of the present invention, the values of all parameters may vary over wide ranges to suit different applications. . Unless the context indicates otherwise, or otherwise understood by one of ordinary skill in the art, terms such as “about” mean within ±20%.

As used herein, including in the claims, the term “and/or” when used in reference to a list of items means one or more of the items in the list, ie at least one of the items in the list, but not necessarily the list It does not mean all items within. As used herein, including in the claims, the term "or" when used in reference to a list of items means one or more of the items in the list, i.e., at least one of the items in the list, but not necessarily all of the items in the list. It does not mean items. "Or" does not mean "exclusive or".

The disclosed aspects, or portions thereof, may be combined in ways not listed above and/or not explicitly claimed. Further, the embodiments disclosed herein may be suitably practiced without any element not specifically disclosed herein. Accordingly, the present invention should not be considered limited to the disclosed embodiments.

As used herein, numerical terms such as “first,” “second,” and “third” are used to distinguish individual pairings from one another, and in any particular embodiment any particular order of pairings. or the total number is not necessarily indicated. Thus, for example, a given embodiment may include only a second pairing and a third pairing.

Claims (23)

A device for increasing the flow capacity of a fluid channel (300) in a downstream direction (310), the fluid channel having channel surfaces (304, 308) configured for liquid flow therethrough, the channel surfaces being discontinuous (110). ), wherein the device:
and fairings 302 defining each fairing surface 312, said fairing surfaces:
positioned completely within the fluid channel;
configured for liquid flow thereafter;
extending at least to the discontinuity from each leading edge (400) of the fairing surface located upstream (306) of the discontinuity to each trailing edge (402) of the fairing surface located downstream of the leading edge;
At the leading edge, the fairing surface abuts the channel surface;
At the trailing edge, the fairing surface abuts the channel surface;
wherein the fairing surface follows a curve that smoothly transitions between the leading edge and the trailing edge. The device of claim 1 , wherein the fairing surface follows an inverse curve that transitions smoothly between the leading edge and the trailing edge. 3. The device of claim 1 or 2, wherein the trailing edge of the fairing surface is located no further downstream than the discontinuity. 4. The device of any preceding claim, wherein the trailing edge of the fairing surface is located downstream of the discontinuity. 5. The device of claim 4, wherein the fairing surface follows at least a 2-cycle inverse curve. 6. The method of claim 1 , wherein the fluid channel defines a volume (109) configured for liquid flow therethrough, at least a portion of the fairing surface between the leading edge and the trailing edge. is displaced into the volume of the fluid channel from a virtual channel surface of the channel without the fairing by a positive distance, measured perpendicular to the downstream direction. 7. A method according to any one of claims 1 to 6, wherein the fluid channel defines a volume (109) configured for liquid flow therethrough, between the leading edge and the trailing edge, each along the downstream direction. At a position of , the fairing surface is displaced into the volume of the fluid channel from a virtual channel surface of the channel without the fairing by a positive distance measured perpendicular to the downstream direction. 8. The method according to any one of claims 1 to 7, wherein between the leading edge and the trailing edge, at each corresponding position along the downstream direction, of the fluid channel perpendicular to the downstream direction and the The device of claim 1 , wherein a cross-sectional fluid flow area measured taking into account fairing is less than or equal to a virtual cross-sectional fluid flow area without the fairing. 9. The discontinuity according to any one of claims 1 to 8, wherein the discontinuity (a) is elbow-shaped, T-shaped or Y-shaped, or (b) comprises an inlet region to a centrifugal pump or rotary valve. A device defined by a portion of a fluidic channel. 10. The device of any one of claims 1 to 9, wherein the fairing is configured for permanent or temporary installation within the fluidic channel. 11. Device according to any preceding claim, wherein the fairing is formed as an integral part of the fluidic channel. 12. The device of any preceding claim, wherein the fairing surface is smooth. 13. The device of any preceding claim, wherein the fairing surface is dimpled, roughened or patterned. 14. The device of claim 13, wherein the fairing surface defines a surface pattern configured to, in response to the flow of fluid along it, cause emission of acoustic signals representative of predetermined flow characteristics of the fluid. 15. A device according to any preceding claim, wherein the fairing comprises a pin (900) and the fairing is configured to pivot about the pin (900). 16. The method of claim 1, wherein the fairing defines a hollow portion (1000) and an aperture (1002) between the hollow portion (1000) and the fluid channel (300), the hollow portion (1000) (1000) and the aperture (1002) are configured to emit a vibroacoustic signal in response to fluid flow across the aperture (1002). 17. The method of any preceding claim, wherein the fairing defines a bladder (1102) in fluid communication with a control port (1106), the bladder (1102) expanding the bladder (1102). and change the shape of the surface 312 of the fairing 302 in response to. 18. The device of claim 17, wherein the fairing (312) defines at least one pressure sensing port (1108) fluidly coupled to each gauge port (1110). 19. The device of claim 18, wherein the gauge port (1110) is fluidly coupled to the control port (1106). 20. The method of any one of claims 1-19, wherein the fairing defines at least one passageway (1200-1202) through the fairing (302), each passageway (1200-1202) comprising the fairing (302). ) fluidly connects each upstream portion to each downstream portion, each passage 1200-1202 defining a respective upstream opening 1204-1206 and a respective downstream opening 1208-1210, each Passages (1200-1202) are configured to allow at least a portion of liquid flowing within the fluid channel (300) to bypass the full profile of the fairing (302). 21. The process of any preceding claim, wherein the fairing (302) comprises an upstream portion (1300) and a downstream portion (1302) connected together by a pivot hinge (1304), the upstream portion (1300) The upstream end of is translationally attached to the channel surface 304, and the two portions 1300 and 1302 pivot in response to translation of the upstream end of the upstream portion 1300, thereby forming the pivot hinge 1304 , configured to extend the downstream end of the upstream portion 1300 and the upstream end of the downstream portion 1302 further into the fluid channel 300 , wherein the fairing 302 extends the upstream portion 1300 a spring (1318) configured to urge the upstream end of the device into a neutral position. 22. The method of any one of claims 1 to 21, wherein the pairing (302):
a first bladder (1402) in fluid communication with a port (1410) downstream of the fairing (302) in the fluid channel (300); and
defining a second bladder (1404) in fluid communication with a port (1412) upstream of the fairing (302) in the fluid channel (300); wherein the first and second bladders (1402-1404) are configured to automatically adjust the shape of the fairing (302) based on respective pressures at the ports (1410-1412). 23. The device of any preceding claim, wherein the channel surface comprises a second discontinuity (1506), the device comprising:
and a second fairing 1600 defining each second fairing surface 1602, the second fairing surface comprising:
positioned completely within the fluid channel;
configured for liquid flow thereafter;
from each leading edge 1604 of the second fairing surface located upstream 1606 of the discontinuity 1506 to each trailing edge 1608 of the second fairing surface located downstream of the leading edge extends at least to the discontinuity 1506;
At the leading edge 1604, the second fairing surface 1602 abuts the channel surface;
At the trailing edge 1608, the second fairing surface 1602 abuts the channel surface;
and the second fairing surface (1602) follows a curve that transitions smoothly between the leading edge (1604) and the trailing edge (1608).

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